How much should you lift at the gym?

How much weight should you lift at the gym?

Selecting the right amount that matches your goals

          We’ve all heard it before; “lift low weights with high reps for toning,” and “lift heavy weights and low reps to get big.” But does the science really support these statements? And how do you know which weights to chose to help you reach your goals at the gym? Today, we’re sharing with you the science behind resistance training intensity and how the amount you lift at the gym impacts your goals.

          Let’s get one thing straight before we go any further. This article is addressing just 1 of at least 5 identified training variables that will effect the outcome of resistance training. The 5 training variables are:

          1. Exercise Choice

          2. Order of Exercise

          3. Load or Intensity*

          4. Volume of Exercise

          5. Rest

In this article, we are singling out #3, load or intensity. (Look for future articles that will address the other 4 variables.) Load or intensity effects 18-35% of the body’s response to resistance exercise and is likely to be one of the most important training variables.

          Since this article is addressing the “load or intensity” we are lifting at the gym, let’s define it. Resistance training intensity is generally defined as the percentage of maximal strength used for a particular exercise. This is also known as the percentage of 1 repetition maximum or “%1RM.” For example, let’s say you can perform one (and only one) bicep curl using the 40 pound dumbbells.  Your 1 repetition maximum (“1RM”) would be 40 pounds, or 100% 1RM.  If you then chose to use the 32 pound dumbbells, this would be 80% of your 1RM. Or, if you used the 15 pound dumbbells for your bicep curls, this would equal about 40% of 1RM.

          This %1RM is specific to each individual person and every single exercise.  For example, my 72 year old father’s 1RM bicep curl might be 30 lbs, while my 22 year old cousin’s 1RM bicep curl might be 55lbs. This 1RM will be different for every body and will change over time as you become stronger. The 1RM needs to be safely calculated to your body for each exercise you perform in order to calculate the %1RM.

SPOILER ALERT: The science shows we need to lift a lot.

If your goals are to:

          1. Increase strength

          2. Maintain muscle mass

          3. Increase muscle hypertrophy

                                                                    . . . You must lift heavy.

In others words, you better pick up those heavier dumbbells instead of the lighter dumbbells during your next workout.

          The science shows that when we lift heavy, the 3 goals stated above are the direct outcome. High intensity resistance training has been shown to produce the greatest increases in strength and hypertrophy while maintaining muscle mass. In other words, when we lift heavy loads, we get the greatest improvements in strength and muscle size, and it helps us maintain our muscle mass as we age.

          Here at AIM, we believe that the 3 goals listed above are three of the most important outcomes we desire from resistance exercise because they lead to disease prevention (diabetes, heart disease, stroke, etc) and help us age gracefully. In other words, the results of lifting heavy improve both our quality of life and the quantity of time we have. Two additional bonus’ of lifting heavy: 1) improved performance for athletics and sports, and 2) helps us look better naked. I think we can all agree that every one of us can benefit from lifting heavy and receiving these results.

So how much is “a lot” to reap the benefits?

Science points us to >80% of 1RM, used routinely.

The maximum results appear between 80-95% of 1RM. Amounts more than 95% or less than 40% 1RM showed minimal or non-existent results.

Going back to our bicep curl analogy; we stated that the 32lb dumbbells were 80% 1RM so this would be an intensity that would lead to improved strength, hypertrophy, and help maintain muscle mass. The 15lb dumbbells would lead to minimal or non-existent results. We all have a limited amount of time in the gym. Why chose a weight that wastes your time and doesn’t lead you to the results you are there working towards? That’s why choosing an appropriate intensity is so important.

A word of caution

          At AIM, we would add that execution, or form, while performing exercises with higher loads is paramount. The combination of bad form + heavy loads = a much higher rate of injury. Therefore, when performing exercises with high intensity, the very moment that the form goes bad is the moment the set is over. Forget counting reps. Your entire focus needs to be on performing each repetition with absolutely perfect form.  If you grab the 32 lbs dumbbells and execute 7 reps with perfect form, but at the start of the 8th rep you cheat or your form goes bad, it’s that 8th/bad repetition where the injury will occur.


          Based on the science and the results that are achievable by lifting heavy, we should all be focusing more of our resistance exercise time at the gym challenging ourselves with higher intensities.  Keep in mind that when grabbing those heavier dumbbells, your form needs to be on point.  Additionally, if you are unsure of the correct form or do not know how to safely calculate your 1RM, please seek out a knowledgable personal trainer who can guide you.



Fry, Andrew. (2004). The Role of Resistance Exercise Intensity on Muscle Fibre Adaptations. Sports medicine (Auckland, N.Z.). 34. 663-79. 10.2165/00007256-200434100-00004.